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array_product

(PHP 5 >= 5.1.0, PHP 7, PHP 8)

array_productCalculate the product of values in an array

Description

array_product(array $array): int|float

array_product() returns the product of values in an array.

Parameters

array

The array.

Return Values

Returns the product as an integer or float.

Examples

Example #1 array_product() examples

<?php

$a
= array(2, 4, 6, 8);
echo
"product(a) = " . array_product($a) . "\n";
echo
"product(array()) = " . array_product(array()) . "\n";

?>

The above example will output:

product(a) = 384
product(array()) = 1

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User Contributed Notes 7 notes

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12
bsr dot anwar at gmail dot com
6 years ago
Here's how you can find a factorial of a any given number with help of range and array_product functions.

function factorial($num) {
return array_product(range(1, $num));
}

printf("%d", factorial(5)); //120
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25
Andre D
17 years ago
This function can be used to test if all values in an array of booleans are TRUE.

Consider:

<?php

function outbool($test)
{
return (bool)
$test;
}

$check[] = outbool(TRUE);
$check[] = outbool(1);
$check[] = outbool(FALSE);
$check[] = outbool(0);

$result = (bool) array_product($check);
// $result is set to FALSE because only two of the four values evaluated to TRUE

?>

The above is equivalent to:

<?php

$check1
= outbool(TRUE);
$check2 = outbool(1);
$check3 = outbool(FALSE);
$check4 = outbool(0);

$result = ($check1 && $check2 && $check3 && $check4);

?>

This use of array_product is especially useful when testing an indefinite number of booleans and is easy to construct in a loop.
up
0
gergely dot lukacsy at streamnet dot hu
6 months ago
Just a little correction for Andre D's answer: "(bool) array_product($array);" is equivalent with the conjunction of each array elements of $array, UNLESS the provided array is empty in which case array_product() will return 1, which will translate to boolean TRUE.

To mitigate this, you should expand the function with an additional check:

<?php

$result
= !empty($check) && !!array_product($check);

?>
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0
biziclop
10 months ago
You can use array_product() to calculate the geometric mean of an array of numbers:

<?php
$a
= [ 1, 10, 100 ];
$geom_avg = pow( array_product( $a ), 1 / count( $a ));
// = 9.999999999999998 ≈ 10
?>
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-1
Marcel G
13 years ago
You can use array_product to calculate the factorial of n:
<?php
function factorial( $n )
{
if(
$n < 1 ) $n = 1;
return
array_product( range( 1, $n ));
}
?>

If you need the factorial without having array_product available, here is one:
<?php
function factorial( $n )
{
if(
$n < 1 ) $n = 1;
for(
$p++; $n; ) $p *= $n--;
return
$p;
}
?>
up
-2
Jimmy PHP
9 years ago
array_product() can be used to implement a simple boolean AND search

<?php
$args
= array('first_name'=>'Bill','last_name'=>'Buzzard');
$values[] = array('first_name'=>'Brenda','last_name'=>'Buzzard');
$values[] = array('first_name'=>'Victor','last_name'=>'Vulture');
$values[] = array('first_name'=>'Bill','last_name'=>'Blue Jay');
$values[] = array('first_name'=>'Bill','last_name'=>'Buzzard');

$result = search_for($values,$args);
var_dump($result);exit;

function
search_for($array,$args) {
$results = array();
foreach (
$array as $row) {
$found = false;
$hits = array();
foreach (
$row as $k => $v) {
if (
array_key_exists($k,$args)) $hits[$k] = ($args[$k] == $v);
}

$found = array_product($hits);
if (!
in_array($row,$results) && true == $found) $results[] = $row;
}

return
$results;
}
?>

Output:

array (size=1)
0 =>
array (size=2)
'first_name' => string 'Bill' (length=4)
'last_name' => string 'Buzzard' (length=7)
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-8
pqpqpq at wanadoo dot nl
16 years ago
An observation about the _use_ of array_product with primes:

$a=$arrayOfSomePrimes=(2,3,11);
// 2 being the first prime (these days)

$codeNum=array_product($a); // gives 66 (== 2*3*11)

echo "unique product(\$a) = " . array_product($a) . "\n";

The 66 can (only) be split into its original primes,
which can be transformed into their place in the row of primes (2,3,5,7,11,13,17,19...) giving (1,2,3,4,5,6,7,8...)

The 66 gives the places {1,2,5} in the row of primes. The number "66" is unique as a code for {1,2,5}

So you can define the combination of table-columns {1,2,5} in "66". The bigger the combination, the more efficient in memory/transmission, the less in calculation.
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